Internal combustion engines



May 13, 1958 J. H. WEAVING INTERNAL COMBUSTION ENGINES Filed June 19, 1957 Inventor Attorneys United States Patent INTERNAL COMBUSTION ENGINES John H. Weaving, Copt Heath, Knowle, England, assignor to The AustinMotor Company Limited, Birmingham, England Application June 19, 1957, Serial No. 666,649

3 Claims. (Cl. 123-90) This invention relates to internal combustion engines of the overhead valve type and of the kind in which the valves are operated by an overhead camshaft as distinguished from those in which the valves are operated by rocker and push-rod mechanism.

It is well-known that with overhead camshaft operation of the overhead valves an engine can be run at higher speeds than with push-rod operation since the reciprocating parts of the valve gear are lighter. Engines with overhead camshaft operation have, however, the disadvantage that it has hitherto been necessary to employ eccentrics, shims or other expensive or inconvenient devices for adjusting the valve clearance, that is to say the clearance necessary to enable the valve to be held on its seat by the valve spring at such times when the valve does not require to be opened to admit or release gas from the cylinder. The present invention has for its object to provide a simple and comparatively inexpensive means for efiecting valve clearance adjustments in engines of the kind referred to.

According to the invention, the means for adjusting valve clearance in an engine of the kind referred to comprises, for each valve, a tappet in the form of a taper slipper which is interposed and adjustable lengthwise between the valve stem and its operating cam, said tappet being mounted for pivotal movement in a plane containing the axis of the valve, preferably one which is coincident with the plane of rotation of said cam., The tappet or taper slipper acts as an abutment between the cam and the valve stem, or a cap thereon, and, by adjusting it longitudinally with respect to its pivotal mounting, the operating clearance can be reduced or increased as may be required according to whether the adjustment is such as to bring a thicker or a thinner portion of the tappet or slipper into the effective position between the valve stem and the cam, whilst the pivotal mounting of the tappet or taper slipper enables it to partake freely of the movements imparted to it by the cam on the one hand and the valve on the other.

The invention will now be described with reference to the embodiment shown in the accompanying drawing which is a fragmentary sectional and elevation of an internal combustion engine of the kind hereinbefore referred to, the section being taken in the axial plane of one of the valves.

Referring to the drawing, the poppet valve 10, which is mounted for axial sliding movement in a valve guide 11 and is loaded on to its seating 12 by the valve spring 13, is operated against its spring loading by a cam 14 on an overhead camshaft 15 through the intermediary of a tappet or taper slipper comprising a spindle 16 having a tapered inner end portion 17 of gradually increasing thickness 01' diameter, said spindle 16 being slidable longitudinally through a bearing member 18 which is mounted for pivotal movement, in the plane or rotation of the cam 14, in a complementary bearing 19 formed or provided 2,834,330 Patented May 13, 1958 in a mounting bracket 20 on the cylinder head 21. The parallel or untapered portion of the spindle 16 passes through a clearance hole at 22 in the mounting bracket 20 and its outer part is screw threaded and fitted, beyond the bearing member 18, with an adjusting nut 23, and also preferably with a lock nut 24, whilst a helical compression spring 25 encircling the inner plain part of said parallelportion of the spindle 16 operates between an abutment 26 thereon and the mounting bracket 20 so as to maintain the bearing member 18 in engagement with the complementary bearing 19 in said bracket 20.

The bearing member 18 and complementary bearing 19 may, as shown, be of part spherical form and it may be necessary or desirable, in some applications, to pro vide means for preventing rotation of the tappet or taper slipper 16, 17 about its own longitudinal axis. Such means may, for example, comprise a slotted guide member (not shown) which retains the tappet or slipper in a plane which is radial to the valve and includes the point about which said tappet or slipper is mounted to pivot.

With the arrangement shown in the drawing, the tappet or taper slipper 16, 17 acts as an abutment between the cam 14 and the top of the stem of the valve 10, and, by adjusting it longitudinally with respect to its pivotal bearing member 19, using the adjusting nut 23 for this purpose, the operating clearance of the valve 10 can be reduced or increased as may be required according to whether the adjustment is such as to bring a thicker or thinner portion of the taper portion 17 into the effective position between the stem of the valve 10 and the cam .14. The pivotal mounting of the tappet or slipper 16, 17 enables it to partake freely of the movements imparted to it by the cam 14 on the one hand and the valve 10 on the other.

Having fully described my invention, what I claim and desire to secure by Letters Patent is:

1. In an internal combustion engine of the overhead valve type in which the valves are operated by an overhead camshaft, means interposed between each valve stem and its operating cam for adjusting valve clearance, comprising a tapered tappet, mean-s for pivotally mounting the tappet for pivotal movement in a plane containing the axis of the valve and coincident with the plane of rotation of the cam, comprising a stationary bracket having an enlarged opening through which the free end of the tappet extends, a spherical bearing surface formed on one side of the bracket, a spherical bearing member carried by the free end of the tappet and cooperating with said bearing surface, resilient means for maintaining said bearing member in bearing contact with said bearing surface, and means for longitudinally adjusting said tappet.

2. The improvement of claim 1 wherein the longitudinal adjusting means includes an adjusting nut threadedly received by the free end of the tappet and engaging the bearing member.

3. The improvement of claim 1 wherein the resilient means is confined between an abutment on the tappet and the other side of the bracket.

References Cited in the file of this patent UNITED STATES PATENTS 1,333,160 Cline Mar. 9, 1920 1,571,175 Bazzoni Jan. 26, 1926 1,694,367 Bartow Dec. 11, 1928 1,733,240 Saives Oct. 29, 1929 1,986,579 Johnson Jan. 1, 1935 2,644,436 Berlyn July 7, 1953 FOREIGN PATENTS 37,516 Sweden Aug. 20, 1913 

